How to control BP

Hypertension is almost inevitable as we age. The famous Framingham Heart Study suggests that those who are normotensive at age 55 face a 90% lifetime risk for developing high BP.1 This is no small matter. Uncontrolled hypertension is linked to atrial fibrillation, MI, heart failure, and stroke.

Older patients with hypertension have unique needs and often suffer comorbid conditions that make selection of appropriate medications important for good BP control as well as minimizing side effects and costs. The elderly also have the lowest rates of BP control.2

Make sure it’s hypertension

Some older patients have thickened, calcified arteries. Consequently, compression of the brachial artery requires a cuff pressure that is much greater than BP attributed to the blood itself. The estimated systolic BP (SBP) and diastolic BP (DBP) may be considerably higher than the directly measured intra-arterial pressure. This effect, called “pseudohypertension,” is suspected when there is a markedly high BP reading in the absence of end-organ damage, when therapy induces dizziness and weakness without an excessive reduction in BP, or when calcification of the brachial arteries is seen on x-ray. In patients diagnosed with hypertension who have one or more of these findings, studies have found the incidence of pseudohypertension to be as high as 25%. The diagnosis can be confirmed only by direct measurement of the intra-arterial pressure.

Osler’s maneuver might allow the diagnosis to be made noninvasively. This technique involves inflating a sphygmomanometer to a level above the SBP, thereby collapsing the radial artery. In this setting, the radial artery will be palpable only if the vascular wall is markedly thickened. However, the results obtained by Osler’s maneuver are poorly reproducible and there is substantial variability depending on the observer.

Be alert for isolated systolic hypertension

Isolated systolic hypertension (ISH), a risk factor for cardiovascular disease, is more common in the elderly (found in nearly 76% of those over age 65) than in younger populations. ISH occurs when the SBP is >140 mm Hg and the DBP is <90 mm Hg. For patients older than 50, control of SBP has been shown to be more important than control of DBP.3

Though the conventional teaching was that ISH did not merit any treatment, a 2004 Cochrane review indicated that treating 19 patients for five years prevents one cardiovascular event, treating 50 patients for five years prevents one cardiovascular death, and treating 63 patients for five years prevents one all-cause death.

Two other independent risk factors for CVD in the elderly include a widened pulse pressure (>50 mm Hg) and a low DBP (<60 mm Hg). A 10-mm-Hg widening of the pulse pressure increases the chances of stroke by 24% and heart failure by 32%. For lower DBPs, the lower the pressure, the higher the risk.

The three-step initial evaluation

First, identify lifestyle issues or risk factors that can contribute to hypertension or future end-organ damage—e.g., high sodium intake, lack of activity, tobacco use, and diabetes. Second, search for identifiable causes. Most patients will have essential hypertension, but a few will have reversible causes (e.g., sleep apnea, drug-related BP, renal disease, primary aldosteronism, renovascular disease, chronic steroid therapy, Cushing’s syndrome, coarctation of the aorta, or thyroid or parathyroid disease). Finally, assess for end-organ damage. This can help the patient understand the need for treatment and provide a prognosis. Table 1 lists the key elements of the initial evaluation.

Successful treatment

Start with lifestyle changes — weight reduction, the Dietary Approach to Stop Hypertension (DASH) eating plan (rich in potassium and calcium), reduced sodium intake, increased physical activity, and reduced alcohol consumption. The DASH eating plan is equal to single-drug therapy in reducing BP.3 Lifestyle modifications should be tried for four to six months for maximum effect. Sedentary patients should be carefully evaluated before beginning an exercise program and considered for a cardiac stress test.

Most patients will not respond to lifestyle modifications alone or will be unable or unwilling to comply with your recommendations. These patients will require drug therapy. In such cases, more than one drug may be needed.4 In fact, patients who are 20 mm Hg over their SBP goal or 10 mm Hg over their DBP goal should be considered for more than one drug at the outset. Medication classes that lower BP effectively include ACE inhibitors, thiazide diuretics, beta blockers, calcium channel blockers, and angiotensin receptor blockers (ARBs).

The recommended initial medication for patients older than 65 is a thiazide diuretic.5 This class of medications has a long track record of efficacy, with strong evidence of reducing morbidity and mortality. Thiazide diuretics are also inexpensive, well tolerated, and do not widen the pulse pressure in patients with ISH. Even for elderly patients requiring multidrug therapy, thiazides should be a mainstay of treatment. Thiazides are equal to ACE inhibitors and calcium channel blockers in decreasing BP, cardiovascular events, and mortality.

Dosages can begin as low as 6.25 mg/day for hydrochlorothiazide, increasing to a maximum of 50 mg/day. Dosages >50 mg/day do not improve BP control and raise the likelihood of side effects. These include hypokalemia, hyponatremia, hyperuricemia, and hyperglycemia, but thiazides do not induce diabetes mellitus. Serious reactions include renal failure and pancreatitis. Monitoring of serum potassium and creatinine is indicated once or twice a year.

Choosing the second drug

After thiazide diuretics, the choice of medications is based on other comorbid conditions. No class of drugs is clearly superior, but ACE inhibitors and ARBs seem to have fewer sexual and cognitive side effects. Patients with CAD may benefit from a beta blocker, and patients with type 2 diabetes can be helped to avoid renal disease by using an ACE inhibitor. Table 2 shows options for alternate or additional therapies after thiazide diuretics.

Beta blockers should not be used as first-line medications for uncomplicated systolic hypertension in the elderly. In a meta-analysis that compared beta blockers with diuretics, beta blockers were less effective for the prevention of cardiovascular, cerebrovascular, and all-cause mortality and more likely to induce diabetes.6 For all older patients, the adage to “start low and go slow” is appropriate to help avoid side effects and ensure compliance. However, most of our elderly patients will eventually require standard doses of medications to achieve adequate BP control. Table 3 provides a partial list of antihypertensive medications with typical dosages.

To encourage compliance, patients should return monthly for follow-up and medication adjustment until their BP goal is reached. Patients with stage 2 hypertension or comorbid conditions may need to be seen more frequently. After the goal has been achieved and BP is stable, routine follow-up visits every three to six months are recommended.

Comorbid conditions, such as associated diabetes or heart failure, plus the need for laboratory tests influence the frequency of visits. Low-dose aspirin therapy should be considered only when BP is controlled because the risk of hemorrhagic stroke is increased in patients with uncontrolled hypertension.

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Resistant hypertension is defined as failure to reach goal on three drugs, including a diuretic. For these patients, consider referral to a hypertension specialist.

Dr. Holman is a captain in the U.S. Navy and program director of the Department of Family Medicine at the Naval Hospital in Camp Pendleton, Calif. The opinions expressed in this article are the author’s and should not be construed as official or as reflecting the views of the Department of the Navy or the Department of Defense.

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